Three.js 自定义shader飞线动画

Flywire

// 引入Three.js
import * as THREE from '../../../../three.js-r133/build/three.module.js';
import output_fragment from './output_fragment.glsl.js'

var model = new THREE.Group(); //声明一个组对象
/**
 * 创建线条模型
 */
var geometry = new THREE.BufferGeometry(); //创建一个缓冲类型几何体
// 三维样条曲线
var curve = new THREE.CatmullRomCurve3([
  new THREE.Vector3(100, 0, -100),
  new THREE.Vector3(0, 80, 0),
  new THREE.Vector3(-100, 0, 100),
]);
//曲线上等间距返回多个顶点坐标
var points = curve.getSpacedPoints(100); //分段数100，返回101个顶点
// setFromPoints方法从points中提取数据赋值给attributes.position
geometry.setFromPoints(points);
var material = new THREE.LineBasicMaterial({
  color: 0x006666, //轨迹颜色
});
//线条模型对象
var line = new THREE.Line(geometry, material);
model.add(line);


var index = 20; //取点索引位置
var num = 15; //从曲线上获取点数量
var points2 = points.slice(index, index + num); //从曲线上获取一段
var curve = new THREE.CatmullRomCurve3(points2);
var newPoints2 = curve.getSpacedPoints(100); //获取更多的点数
var geometry2 = new THREE.BufferGeometry();
geometry2.setFromPoints(newPoints2);
// 每个顶点对应一个百分比数据attributes.percent 用于控制点的渲染大小
var percentArr = []; //attributes.percent的数据
for (var i = 0; i < newPoints2.length; i++) {
  percentArr.push(i / newPoints2.length);
}
var percentAttribue = new THREE.BufferAttribute(new Float32Array(percentArr), 1);
geometry2.attributes.percent = percentAttribue;
// 批量计算所有顶点颜色数据
var colorArr = [];
for (var i = 0; i < newPoints2.length; i++) {
  var color1 = new THREE.Color(0x006666); //轨迹线颜色 青色
  var color2 = new THREE.Color(0xffff00); //黄色
  var color = color1.lerp(color2, i / newPoints2.length)
  colorArr.push(color.r, color.g, color.b);
}
// 设置几何体顶点颜色数据
geometry2.attributes.color = new THREE.BufferAttribute(new Float32Array(colorArr), 3);

// 点模型渲染几何体每个顶点
var PointsMaterial = new THREE.PointsMaterial({
  // color: 0xffff00,
  size: 5*5.0, //点大小
  vertexColors: THREE.VertexColors, //使用顶点颜色渲染
  transparent:true,//开启透明计算
  depthTest:false,
});
var flyPoints = new THREE.Points(geometry2, PointsMaterial);
model.add(flyPoints);
// 修改点材质的着色器源码(注意：不同版本细节可能会稍微会有区别，不过整体思路是一样的)
PointsMaterial.onBeforeCompile = function (shader) {
  // 顶点着色器中声明一个attribute变量:百分比
  shader.vertexShader = shader.vertexShader.replace(
    'void main() {',
    [
      'attribute float percent;', //顶点大小百分比变量，控制点渲染大小
      'void main() {',
    ].join('\n') // .join()把数组元素合成字符串
  );
  // 调整点渲染大小计算方式
  shader.vertexShader = shader.vertexShader.replace(
    'gl_PointSize = size;',
    [
      'gl_PointSize = percent * size;',
    ].join('\n') // .join()把数组元素合成字符串
  );

  shader.fragmentShader = shader.fragmentShader.replace('#include ', output_fragment);
};
// 飞线动画
var indexMax = points.length - num; //飞线取点索引范围
function animation() {
  if (index > indexMax) index = 0;
  index += 1
  points2 = points.slice(index, index + num); //从曲线上获取一段
  var curve = new THREE.CatmullRomCurve3(points2);
  var newPoints2 = curve.getSpacedPoints(100); //获取更多的点数
  geometry2.setFromPoints(newPoints2);

  requestAnimationFrame(animation);
}
animation();

plane();//设置一个地面
function plane() {
    var gridHelper = new THREE.GridHelper(300, 15, 0x003333, 0x003333);
    model.add(gridHelper);
    var geometry = new THREE.PlaneGeometry(310, 310); 
    var material = new THREE.MeshLambertMaterial({
        // map: texture,
        color: 0xffffff,
        transparent: true,
        opacity: 0.1,
        side: THREE.DoubleSide,
    });
    var mesh = new THREE.Mesh(geometry, material);
    mesh.position.y = 1
    model.add(mesh);
    mesh.rotateX(-Math.PI / 2);
}


export {
  model
}

glsl 

export default /* glsl */`
#ifdef OPAQUE
diffuseColor.a = 1.0;
#endif

// https://github.com/mrdoob/three.js/pull/22425
#ifdef USE_TRANSMISSION
diffuseColor.a *= transmissionAlpha + 0.1;
#endif

// 设置透明度变化
float r = distance(gl_PointCoord, vec2(0.5, 0.5));
// diffuseColor.a = diffuseColor.a*(1.0 - r/0.5);//透明度线性变化
diffuseColor.a = diffuseColor.a*pow( 1.0 - r/0.5, 6.0 );//透明度非线性变化  参数2越大，gl_PointSize要更大，可以直接设置着色器代码，可以设置材质size属性
gl_FragColor = vec4( outgoingLight, diffuseColor.a );
`;